bisecting fixing commit since 59456c9cc40c8f75b5a7efa0fe1f211d9c6fcaf1 building syzkaller on a2fe1cb58994e43fb14f141ecd6e6dcce9bb697a testing commit 59456c9cc40c8f75b5a7efa0fe1f211d9c6fcaf1 compiler: gcc version 8.4.1 20210217 (GCC) kernel signature: 626673fcfea27dfc56f752ebe50e496e7550eaafaac1ed537f983dfe5676ccaf run #0: crashed: BUG: soft lockup in tipc_conn_recv_work run #1: crashed: BUG: soft lockup in cleanup_net run #2: crashed: BUG: soft lockup in tipc_topsrv_accept run #3: crashed: BUG: soft lockup in cleanup_net run #4: crashed: BUG: soft lockup in cleanup_net run #5: crashed: BUG: soft lockup in tipc_conn_recv_work run #6: crashed: BUG: soft lockup in cleanup_net run #7: crashed: BUG: soft lockup in cleanup_net run #8: crashed: BUG: soft lockup in cleanup_net run #9: OK run #10: OK run #11: OK run #12: OK run #13: OK run #14: OK run #15: OK run #16: OK run #17: OK run #18: OK run #19: OK reproducer seems to be flaky testing current HEAD b172b44fcb1771e083aad806fa96f3f60e2ddfac testing commit b172b44fcb1771e083aad806fa96f3f60e2ddfac compiler: gcc version 8.4.1 20210217 (GCC) kernel signature: 3027de1f0a21a7e95746c30911b7fde5b5af3daeac0af0f23de502e74213c9f8 run #0: crashed: BUG: soft lockup in cleanup_net run #1: crashed: BUG: soft lockup in tipc_topsrv_accept run #2: crashed: BUG: soft lockup in cleanup_net run #3: crashed: BUG: soft lockup in cleanup_net run #4: crashed: BUG: soft lockup in tipc_topsrv_accept run #5: crashed: BUG: soft lockup in cleanup_net run #6: crashed: BUG: soft lockup in cleanup_net run #7: crashed: BUG: soft lockup in tipc_conn_recv_work run #8: crashed: BUG: soft lockup in tipc_topsrv_accept run #9: crashed: BUG: soft lockup in cleanup_net run #10: crashed: BUG: soft lockup in cleanup_net run #11: crashed: BUG: soft lockup in cleanup_net run #12: OK run #13: OK run #14: OK run #15: OK run #16: OK run #17: OK run #18: OK run #19: OK Reproducer flagged being flaky revisions tested: 2, total time: 45m9.034507108s (build: 21m21.662978707s, test: 23m25.169902076s) the crash still happens on HEAD commit msg: Linux 4.19.206 crash: BUG: soft lockup in cleanup_net IPVS: ftp: loaded support on port[0] = 21 Bluetooth: hci3: command 0x0419 tx timeout Bluetooth: hci4: command 0x0419 tx timeout Bluetooth: hci1: command 0x0419 tx timeout IPVS: ftp: loaded support on port[0] = 21 watchdog: BUG: soft lockup - CPU#0 stuck for 23s! [kworker/u4:0:7] Modules linked in: irq event stamp: 607015 hardirqs last enabled at (607014): [] trace_hardirqs_on_thunk+0x1a/0x1c hardirqs last disabled at (607015): [] trace_hardirqs_off_thunk+0x1a/0x1c softirqs last enabled at (601702): [] spin_unlock_bh include/linux/spinlock.h:374 [inline] softirqs last enabled at (601702): [] release_sock+0x11f/0x180 net/core/sock.c:2892 softirqs last disabled at (601704): [] spin_lock_bh include/linux/spinlock.h:334 [inline] softirqs last disabled at (601704): [] tipc_topsrv_stop net/tipc/topsrv.c:702 [inline] softirqs last disabled at (601704): [] tipc_topsrv_exit_net+0x1fe/0x4d0 net/tipc/topsrv.c:722 CPU: 0 PID: 7 Comm: kworker/u4:0 Not tainted 4.19.206-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: netns cleanup_net RIP: 0010:tipc_topsrv_stop net/tipc/topsrv.c:699 [inline] RIP: 0010:tipc_topsrv_exit_net+0x1e0/0x4d0 net/tipc/topsrv.c:722 Code: 45 31 f6 48 b8 00 00 00 00 00 fc ff df 48 c1 ea 03 48 01 d0 48 89 45 c0 49 63 f6 48 89 df e8 27 b7 2f 00 48 85 c0 48 89 45 d0 <74> 1c 4c 89 ef e8 d6 01 58 00 48 8b 45 d0 48 89 c7 e8 9a d7 ff ff RSP: 0018:ffff8880b599fbd0 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13 RAX: 0000000000000000 RBX: ffff8880b5162d40 RCX: 0000000000000006 RDX: 0000000000000000 RSI: ffffffff99d3b4af RDI: ffff8880b5162d40 RBP: ffff8880b599fc10 R08: ffff8880b5162d40 R09: ffff8880b5162d80 R10: 0000000000000000 R11: 0000000000000040 R12: ffff8880806a4a40 R13: ffff8880b5162d90 R14: 0000000099d3b4af R15: ffff8880b5162e30 FS: 0000000000000000(0000) GS:ffff8880ba200000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000055b5737ca988 CR3: 0000000097b02000 CR4: 00000000001406f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: ops_exit_list.isra.0+0x8b/0x120 net/core/net_namespace.c:153 cleanup_net+0x368/0x850 net/core/net_namespace.c:553 process_one_work+0x7b9/0x15a0 kernel/workqueue.c:2153 worker_thread+0x85/0xb60 kernel/workqueue.c:2296 kthread+0x347/0x410 kernel/kthread.c:259 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415 Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 skipped: idling at native_safe_halt+0x12/0x20 arch/x86/include/asm/irqflags.h:60 ---------------- Code disassembly (best guess): 0: 45 31 f6 xor %r14d,%r14d 3: 48 b8 00 00 00 00 00 movabs $0xdffffc0000000000,%rax a: fc ff df d: 48 c1 ea 03 shr $0x3,%rdx 11: 48 01 d0 add %rdx,%rax 14: 48 89 45 c0 mov %rax,-0x40(%rbp) 18: 49 63 f6 movslq %r14d,%rsi 1b: 48 89 df mov %rbx,%rdi 1e: e8 27 b7 2f 00 callq 0x2fb74a 23: 48 85 c0 test %rax,%rax 26: 48 89 45 d0 mov %rax,-0x30(%rbp) * 2a: 74 1c je 0x48 <-- trapping instruction 2c: 4c 89 ef mov %r13,%rdi 2f: e8 d6 01 58 00 callq 0x58020a 34: 48 8b 45 d0 mov -0x30(%rbp),%rax 38: 48 89 c7 mov %rax,%rdi 3b: e8 9a d7 ff ff callq 0xffffd7da